Prior art methods of measuring gut transit time typically involve feeding an animal charcoal via oral gavage, and then either placing the animal in a specially configured cage and manually observing the animal, or killing the animal.
Gut transit time is also known as intestinal motility. Weaknesses of prior art include the time consuming and invasive practice of oral gavage, the expensive, time consuming and error-prone manual observation step, stressing an animal by placement in an unfamiliar cage, and poor time resolution and poor time accuracy of manual observations. Another weakness is the inability to take a sequence of measurements over days to track changes in gut transit time. Another weakness is the inability to multi-house animals. Yet another weakness is the practical limitation of starting the time interval during the animal's normally active, nocturnal time. Some prior art has the weakness of killing the animal.